Hole saw



HOLE SAW Zoltan O. St. Palley, Branford, Conn.

Application February 28, 1955, Serial No. 491,115

3 Claims. (Cl. 29103) My invention relates to improvements in hole saws, and particularly to improvements in the hole saw shown and described in Patent No. 2,674,026 granted to me on April 6, 1954. It has particular utilityin BX cable armor cutters, having deeply recessed split annular hole saw blades, such as described in my Patents No. 2,642,651 issued on June 23, 1953, and No. 2,687,560 issued on August 31, 1954.

tates Patent O One of the objects of my invention is to provide a hole saw in which the blade can be removed and replaced easily and conveniently by the rotation of a screw by means of a screw driver.

Another object of my invention is to provide a hole saw in which the screw, which draws the blade into the holder and removes the blade from the holder, will effect also the clamping and the unclamping of said blade, thereby increasing greatly theease and convenience of the renewal of the blade.

A further object of my invention is to provide a hole saw in which the blade is secured to the holder. very effectively by the combination of a positive mechanical coupling and a powerful frictional clamping, giving ample support for the thinnest blade and precluding the slipping of the blade in the holder.

Other objects and advantages of my invention will be apparent during the course of the following description.

In the accompanying drawing, forming a part of this application wherein, for the purpose of illustration, are shown a preferred embodiment and a modified form of my invention,

Figure l is a central sectional view of the preferred form of my hole saw, with the blade clamped in position,

Figure 2 is a central sectional view of the same, with the blade partly extracted,

Figure 3 is an end view of the same,

Figure 4 is an end view of the hole saw blade,

Figure 5 is a side view of the same blade,

Figure 6 is a cross sectional view on line 6-6 of Figure 1,

Figure 7 is a plan view of the clamping ring,

Figure 8 is a side view of the sameclamping ring,

Figure 9 is a plan view of the annular spring,

Figure 10 is a side view of the same annular spring,

Figure 11 is a plan view of a modified form of the clamping ring,

Figure 12 is a side view of the same modified ring,

Figure 13 is a central sectional view of a modified form of my hole saw, with the blade clamped in position,

Figure 14 is a central sectional view of the same modified form of my hole saw, with the blade partly extracted,

Figure 15 is a plan view of a modified form of the annular spring,

Figure 16 is a side view of the same modified form of the annular spring.

In the drawing, wherein like numerals are employed to designate like parts, the numeral 1 designates the hole saw holder, some times called the mandrel, which has a coaxial cylindrical cavity 2, and a groove 3 disposed in the lice side wall of said cavity and extending to the open end of said cavity. Recessed in said cavity, adjacent to its side wall, is a cylindrical split annular hole saw blade 4, having a slot 5. In the preferred form of my invention this slot is circular, as illustrated in Fig. 5, but it is within the spirit of my invention to employ slots of various shapes and in various numbers.

Disposed within said hole saw blade 4 is the split annular spring 8, which surrounds the clamping ring 6; This clamping ring6 "is radially expansible, being made up of segments held together by the resilient spring 8. In the preferred fornnthe clamping ring consists of four segments, as illustrated in Fig. 7, this number, however, may vary in my invention. For example, Fig. 11 shows. two segments. that one of these segments is provided with a radial stud 7, which passes through the slot 5 of the blade 4, and extends into the groove 3 of the holder 1. In the preferred form, shown in Figs. 1 and 2, this stud 7 will pass also through a hole in theannular spring 8 before entering the slot 5 of the blade 4.

Adjoining said cavity 2, the holder 1 base coaxial threaded hole 13, containing and engaging the screw 9, which has a neck 10, forming the shoulder 11, and a conical head 12 provided with a slot for the application of a screw driver. This neck 10 and head 12 are surrounded by the said clamping ring 6, the central opening of which is conical having the same slope as the head and extending into the groove 3, will effectively anchor the blade 4 in the cavity of the holder 1. g I

The other result of the present arrangement" is that,

as'the minimum inside diameter of the clamping ring 6 is smaller than either of the shoulder 11 or thehead 12,

when the screw9 is turned to move outwardly, thejshoulder 11 will engage the clamping ring 6 and will cause it to move out of the cavity 2, together with the hole saw blade 4. Conversely, when said screw 9 is rotated tomove inwardly, the hea'd'12 will engage and move theclamping ring 6, and the connected blade 4,'into the cavity.2 of the holder 1.

'The' two extreme positions of the screw 9 are time trated in Figs. 1 and 2, respectively. In Fig. 1 the screw is turned in tightly, securely clamping the blade 4. In Fig. 2 the screw is screwed out completely from the threaded hole 13, so that this screw 9, together with the clamping ring 6, annular spring 8 and the hole saw blade 4, can be removed from the cavity 2 as a self-contained assembly.

Figs. 3 and 6 of the drawing, showing an end view and a cross sectional view, respectively, give further details regarding the concentric arrangement of the blade 4, spring 8, clamping ring 6, and the screw 9.

Figs. 4 and 5 illustrate the split annular hole saw blade. I

The preferred forms of the clamping ring and the annular spring are illustrated in Figs. 7, 8, and 9, 10, respectively. In this form the spring 8 has a hole, located to correspond to the slot 5 of the blade 4.

Figs. 11 and 12 show a modified form of the clamping ring 6, with only two segments. In addition to stud 7, this form has also a second stud 14 which, however, is shorter than the combined thickness of the blade 4' and the spring 8, consequently, it requires no groove 3.

Figs. 13 and 14 illustrate a modified form of my'hole It is an essential feature of my invention saw in the clamped and in the unclamped positions, respectively. In this form the spring 8 is"narrower and 'is recessed into the outer surface of the clamping ring 6. Aee nding t ss 15an i iih asarinsis nli ann lar an ismadeefa t silientnar ewhandvaaalt na i e fem, sp n 1831 1 1 eqa tmelei. t etili mw r iee ihel ea ei w hone mommie lh vqp r t q smy nventianrwi wbeasiioi pws; ltsafi. e sent a f atur Q mrhelesawut at hese evv 9 performs the following four iunctions: itdraivfiheyhgle aw lad int t e cavi y Qitheho deri teiamp th blad securely Ihecav y;i 'unelanips he bla nditmova heh ad ou o theeav ty- A i esaltofithhimul iple u c onin of e. e e v, thehrenew iq i h sw rn blad equi e vervl tt i and fiqr hich baamportan attache tethee ampi s dingh stu 7 an: ei emeved r m t e o de esaaassehxblvhen th .Q e aw blade be n res lien and. spl t w l bes etnexedi r m hestnd'l v.Qf t e clea sing fins and. wi s elreplaee by a new blade. Following this, said assemhlyQinc luding the ne a e, il heinse te ia elthes vitx inlh ipesiien sho n. i wF -s d,v byrmeane fijaise e r river the crew 9 l b r a ed inw rd y; causin i hesblade t0,

move int h c y o thehplde u til the blade eaehe h n .ot h a ty- Iheinn he in rdmrQtatiQa o hese l caus th exp n pnto q oth lanipiagrr ag by he al d 2, here y eff ting the fric i na clamping of the blade in the holder.

It is to be unde sto dtha th s qu ebf mv i v n io he ew t shown nd e erib darelebe .takrennas. exa -v P s tsam an t a ar eusehanse in th is z ashape and in the, ar a e ent oi Parts may besre tted t9 ou d parti g fr m thes piri' oft/my invent nicmh seen QithesnbiQ nedeIa m -V ,1 Al ele aw holde havin weyl n xiea sav tv and a, groov invthersides va l. ofsaidsar tynextea ins 9 th open end of said cavity; a split annular saw blade reqessed in, ai cav t .sa di ade havi g a s t; af p itz ennular spring coaxially disposed within said saw blade; an expansible -clamping ring, consisting of segments surrounded and held together by said spring; a stud secured to one of said segments and being adapted to pass through said slot of the saw blade and to extend into said groove of the holder; a screw coaxially disposed in said cavity with threaded connection with said holder and having a shoulder and a conical head disposed-insidesaid clamping ring; said shoulder being adapted to engageand to move said clamping ring outwardly from said cavity when said screw being unscrewed fromsaid holder; and said conical head being adapted to move said clamping ring inwardly to the-end of said cavity, and then to expand said clamping ring, causing it to press .saidsawblade againstthe side wall of said cavity, when said screw being screwed inwardly into said holder.

2. A hole saw holder having a cylindrical cavity with a gropvein theside wallv ofsaidcavity; ,a split annular sawblade recessed in said cavity, said bla-dezhaving arslo t; a ezsp ns hl c mp ng, g, s rrounded y a .ei e a spring disposed inside saidrsaw. blade; a stud securedto said clamping, ring and extending through said slot ofthe saw blade' into' said groove of the holder; a screw thread:

edly connected with saidholder and having a shoulder and a conical head disposed inside said clamping ring;

d. shoulde v e ng; a ap ed. o mo e said c ampnst ls eutne dlytre g aid c vit e Said. c e b n e.- atedtoutv ar y, and a ad be g adap m e said clamping ring into said cavity and to expand said elampina ias, us n t re a p s d b d with nea avity, when said ere bein o t d nwa d y t t hqlde .3. A h le aw reemp is n r de vias c ind ica out of said cavity when the screw ,islvtur -ned to advance outwardly, ,and a head adaptedntoflmove said ring into saidmeavity.andv t expand ai in w ai scr w i urn dl adva ce nw r y t h ho de f e e e i es i nfile Q h sp tem UNITED STATES PATENTS 1;017;9.6 8 Greenleaf Feb. 20, 1-912 1,'212l;633: Short "Jan. 9, 1917 136795 15- ACone Aug. '7, 1928 2,674,026 St. Palley Apr.-6, I954 

